A spectrum analyzer has conventionally been used to measure an optical spectrum. The spectrum analyzer includes spectrometers and photodetectors (refer to a patent document 1 (Japanese Laid-Open Patent Publication (Kokai) No. 2002-340673 (ABSTRACT)), for example).
Moreover, a wavelength characteristics measuring unit which measures wavelength characteristics of a device under test such as an optical fiber includes a light source which makes light incident on a device under test, and a photodetector which detects the light which has transmitted through the device under test.
It may be necessary to successively measure the wavelength characteristics and the optical spectrum of a device under test. On this occasion, the wavelength characteristics measuring unit is first used, and the spectrum analyzer is then used.
However, when the wavelength characteristics measuring unit is used, the spectrometer and the photodetector of the spectrum analyzer cannot be used. When the spectrum analyzer is used, the light source and the photodetector of the wavelength characteristics measuring unit cannot be used.
In view of the foregoing problem, an object of the present invention is to efficiently use members of the spectrum analyzer and the wavelength characteristics measuring unit. Namely, the object is to provide a device with the minimum configuration which can measure the wavelength characteristics and the optical spectral characteristics.